1. Field of the Invention
The invention relates to a sliding window and, more particularly, to one intended for use in automobiles, and one which is raised and lowered electrically and is equipped with a safety device that includes to a proximity dectector.
2. Description of the Prior Art
U.S. Pat. No. 3,651,389 describes a sliding electrically driven vehicular window having a control circuit made up of discrete electronic elements. Because of this, the electronic control circuit is relatively bulky and, as such, must be positioned inside the door which houses the window, for example, in the vicinity of the drive motor for the window. In order to achieve a high degree of sensitivity such that control circuit can respond to contact with a clothed portion of human body, for example, a gloved hand, it is necessary to connect this circuit to a pickup mounted on the window glass by means of a shielded conductor, in particular, a coaxial cable.
Since the coaxial cable is physically attached at only its two ends, it is completely suspended between the control circuit and the pickup. Consequently, the rest of the cable, i.e., its body, swings inside the door casing whenever, for example, the window glass is raised or lowered, or whenever the door is slammed.
This type of construction disadvantageously has several drawbacks. First, there is no guarantee that an unsuitable control circuit will not be mounted in the vehicle. Specifically because of the high sensitivity of the control circuit, it is often necessary to adjust the control circuit as the time of its installation in the vehicle, to the particular values of the ohmic resistance and capacitance of the pickup to which the control circuit is to be connected in order to avoid any operating trouble. However, these values essentially depend upon the shape and dimensions of the glass and the window frame and thus often vary widely depending upon the model of the vehicle. This is true even within any given type, e.g. cars, trucks and the like. Thus, it is not sufficient to make these adjustments according to just the type of vehicle. Consequently, a control device, adjusted for one type of vehicle and thereafter installed on another, may operate in a faulty manner.
Second, the suspended cable produces another drawback. Specifically, since these cables are relatively rigid, the effect of their continual bending caused by the continual movement of the cable from, for example, normal repetitive raising and lowering of the window, will over time weaken the cable connections. This could eventually break one or both of these connections.
The final drawback is that these cables do not provide sufficient protection against the generation of spurious signals. In particular, water or at least moisture, is often found inside a door of a vehicle and as such will often penetrate the cable. This in turn disadvantageously causes capacitance variations which can cause the safety device to operate at the wrong moment. Spurious signals can also be generated from the simple movement of the cables within the body of the door, caused for example, by the door being opened or closed.